Pinpoint Test I: Incorrect/Erratic Direction Of Airflow From Outlets - Manual Climate Control
Climate Control System
Pinpoint Tests
Pinpoint Test I: Incorrect/Erratic Direction of Airflow From Outlets - Manual Climate Control
Normal Operation
Under normal operation, the function selector switch is provided vacuum from the engine. When a position is selected, vacuum is applied to the desired vacuum control motor that is connected to the mode door to be controlled.
A leak or blockage of the vacuum source line to the HVAC system will result in the following default conditions:
- Airflow will be from the defrost outlets only.
- The air inlet door will remain in the fresh air position only.
- The coolant control valve will allow coolant flow to the heater core at all times.
This pinpoint test is intended to diagnose the following:
- Function selector switch
- Heater control valve
- Vacuum control motor
- Stuck or bound linkage or door
- Leaking or plugged vacuum hose
PINPOINT TEST I: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLETS - MANUAL CLIMATE CONTROL
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I1 CHECK THE SYSTEM AIRFLOW
- Start the engine.
- Set the blower motor speed to maximum.
- Check for proper airflow in each function selector switch position at engine idle and under acceleration.
- Road test the vehicle and recheck the airflow during the road test.
- Is the airflow correct in each function selector switch position?
Yes
GO to I2.
No
If the airflow is from only the defrost outlet in all settings, GO to I3.
CARRY OUT the Function Selector Vacuum Switch component test. If the switch leaks or is blocked, INSTALL a new climate control assembly. TEST the system for normal operation. If the switch tests OK and: Function Selector Vacuum Switch
If there is no airflow from the panel outlets in PANEL mode, GO to I11 and diagnose the panel door vacuum control motor.
If there is no airflow from the floor outlets in FLOOR mode, GO to I11 and diagnose the floor door vacuum control motor.
If there is no airflow from the defrost outlets in DEFROST mode, GO to I11 and diagnose the defroster door vacuum control motor.
If there is some airflow from the defrost outlets in PANEL and FLOOR modes, GO to I11 and diagnose the defroster door vacuum control motor.
If there is some airflow from the panel outlets in DEFROST and FLOOR modes, GO to I11 and diagnose the panel door vacuum control motor.
If there is some airflow from the floor outlets in DEFROST and PANEL modes, GO to I11 and diagnose the floor door vacuum control motor.
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I2 CHECK THE AIR INLET DOOR OPERATION
- Select PANEL mode.
- Select the highest blower motor setting.
- Observe airflow noise.
- Select MAX A/C mode.
- During the road test, does the airflow noise increase when the MAX A/C mode is selected?
Yes
The system is operating normally.
No
CARRY OUT the Function Selector Vacuum Switch component test. If the switch leaks or is blocked, INSTALL a new climate control assembly. If the switch tests OK, GO to I11 and diagnose the air inlet door vacuum control motor. Function Selector Vacuum Switch
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I3 CHECK THE VACUUM CHECK VALVE
- Ignition OFF.
- Disconnect: Vacuum Check Valve.
- NOTE: The vacuum check valve is located in the passenger side, rear area of the engine compartment, near the heater control valve.
- Connect the vacuum pump to the each port on the vacuum check valve and attempt to pull a vacuum.
- Can a vacuum be pulled on only one side of the vacuum check valve and not the other?
Yes
GO to I4.
No
INSTALL a new vacuum check valve. TEST the system for normal operation.
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I4 CHECK FOR VACUUM AT THE CHECK VALVE
- Connect the vacuum pump to the vacuum source line to the check valve from the engine intake manifold.
- Start the engine.
- Check for manifold vacuum.
- Is manifold vacuum present at the check valve vacuum source line?
Yes
GO to I5.
No
REPAIR or INSTALL a new check valve vacuum source line harness. TEST the system for normal operation.
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I5 CHECK THE FUNCTION SELECTOR SWITCH VACUUM SOURCE LINE FOR BLOCKAGE
- Ignition OFF.
- Disconnect: Function Selector Switch Vacuum Connector.
- With the vacuum check valve disconnected, connect the vacuum pump to the function selector switch vacuum source line (black) and attempt to pull a vacuum. (Pulling a vacuum here would indicate a restricted or blocked vacuum source line.)
- Does air flow freely through the vacuum source line (no vacuum)?
Yes
GO to I6.
No
REPAIR or INSTALL a new function selector switch vacuum source line. TEST the system for normal operation.
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I6 CHECK THE FUNCTION SELECTOR SWITCH VACUUM SOURCE LINE FOR LEAKS
- Connect: Vacuum Check Valve.
- Apply 51 kPa (15 in-Hg) of vacuum to the selector switch vacuum source line (black) using the vacuum pump.
- Does the function selector switch vacuum source line hold the vacuum?
Yes
INSTALL a new climate control assembly. TEST the system for normal operation.
No
GO to I7.
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I7 CHECK THE VACUUM RESERVOIR FOR LEAKS
- Disconnect the vacuum reservoir line at the vacuum reservoir.
- Plug the vacuum reservoir line at the vacuum reservoir connection.
- Apply 51 kPa (15 in-Hg) of vacuum to the selector switch vacuum source line (black) using the vacuum pump.
- Does the function selector switch vacuum source line hold the vacuum?
Yes
INSTALL a new vacuum reservoir. TEST the system for normal operation.
No
GO to I8.
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I8 CHECK THE HEATER CONTROL VALVE VACUUM SWITCH CIRCUIT
- Disconnect: Heater Control Valve Vacuum Switch.
- NOTE: The heater control valve vacuum switch is located on the RH side of the heater core and evaporator core housing, attached to the temperature blend door shaft. The control valve vacuum switch is accessible through the glove compartment opening.
- Using a golf tee or equivalent, plug the vacuum source line (black) port of the heater control valve vacuum switch vacuum harness.
- Apply 51 kPa (15 in-Hg) of vacuum to the selector switch vacuum source line (black) using the vacuum pump.
- Does the function selector switch vacuum source line hold the vacuum?
Yes
GO to I9.
No
REPAIR the vacuum line to the heater control valve vacuum switch or INSTALL a new vacuum source line harness. TEST the system for normal operation.
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I9 CHECK THE HEATER CONTROL VALVE VACUUM SWITCH
- Apply 51 kPa (15 in-Hg) of vacuum to the heater control valve switch vacuum motor line (gray) using the vacuum pump.
- Does the heater control valve switch vacuum motor line hold the vacuum?
Yes
INSTALL a new heater control valve vacuum switch. TEST the system for normal operation.
No
GO to I10.
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I10 CHECK THE HEATER CONTROL VALVE VACUUM MOTOR CIRCUIT
- Disconnect the vacuum line from the heater control valve and plug the vacuum line (gray) at the heater control valve.
- Apply 51 kPa (15 in-Hg) of vacuum to the heater control valve vacuum motor line (gray) using the vacuum pump.
- Does the heater control valve vacuum motor line hold the vacuum?
Yes
INSTALL a new heater control valve. TEST the system for normal operation.
No
REPAIR or INSTALL a new heater control valve vacuum line. TEST the system for normal operation.
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I11 CHECK THE VACUUM CONTROL MOTOR LINE FOR LEAKS
- Ignition OFF.
- Disconnect: Function Selector Switch Vacuum Connector.
- Disconnect: Vacuum Control Motor (noted in Step I1).
- Plug the vacuum control motor line at the vacuum control motor connection.
- Apply 51 kPa (15 in-Hg) of vacuum to the appropriate vacuum control motor line (noted in Step I1) at the function selector switch vacuum connector using the vacuum pump. using the following chart:
- Does the vacuum control motor line hold the vacuum?
Yes
GO to I12.
No
REPAIR or INSTALL a new vacuum harness. TEST the system for normal operation.
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I12 CHECK THE VACUUM CONTROL MOTOR LINE FOR BLOCKAGE
- Remove the plug from the vacuum control motor line.
- Connect the vacuum pump to the appropriate vacuum control motor line (noted in Step I1) at the function selector switch vacuum connector using the following chart and attempt to pull a vacuum.
- Does air flow freely through the vacuum control motor line (no vacuum)?
Yes
GO to I13.
No
INSTALL a new vacuum harness. TEST the system for normal operation.
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I13 CHECK THE MODE DOOR LINKAGE AND MOVEMENT
- Inspect the mode door linkage and verify correct movement of the mode door.
- Is the mode door or mode door linkage broken, binding or otherwise obstructed?
Yes
REPAIR the mode door or mode door linkage as necessary. TEST the system for normal operation.
No
INSTALL a new vacuum control motor. TEST the system for normal operation.
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